1. Field of the Invention
The present invention relates to a clamping mechanism for releasably mounting a transfer bar to a transfer press.
2. Description of the Prior Art
Transfer machines used to move parts from station to station between presses are well known in the industry. Transfer machines of this type include a mechanism to provide motion to a pair of horizontal links that in turn provide motion to a transfer bar. The transfer bar mounts at the end of the horizontal links and includes specialized tooling that is designed to engage and hold a specific type of work piece. Typically, two such transfer machines are positioned opposite each other and the transfer bars are driven to extend, and grab the work piece between opposing pairs of tooling mounted on the transfer bars. When the tooling has been extended and the work piece engaged, the horizontal links move the transfer bar up vertically, forward horizontally, and downward into the next press station. The horizontal links then retract the transfer bar and disengage the tooling from the work piece and return the transfer bar to a starting position. This method of transferring work pieces between stations is well known in the art and described in U.S. Pat. Nos. 4,833,908 and RE. 34,581.
Depending on the size and material of the work piece, the tooling and the transfer bar required to carry the tooling can be heavy and difficult to handle. The tooling must be designed to engage and hold a specific type of work piece, therefore the tooling is specialized and can only be used with a particular work piece. That means when a different type of work piece is to be processed, the tooling on the transfer bar must be changed. This process is time consuming, as there may be many pairs of tools to change. An alternative is to change the entire transfer bar. This raises difficulties due to the weight of the transfer bar and the tooling. The transfer bar must be mounted securely to the horizontal links to insure that the weight of the transfer bar and the tooling mounted to the transfer bar will be adequately supported. One method of attachment is to simply bolt the transfer bar onto the end of the horizontal links. Typically, this is done by inserting the distal end of the horizontal link into an opening in the transfer bar. In order to accommodate the horizontal link, and maintain the structural integrity of the transfer bar, an insert is welded within the transfer bar. The end of the horizontal link fits within the insert, and a bolt holds the transfer bar onto the end of the horizontal link. The tolerance fit between the insert and the horizontal link is very tight, so the alignment of the insert and the horizontal link must be nearly perfect to allow the transfer bar to be mounted. Due to the size and weight of the transfer bar and tooling, aligning the transfer bar is awkward and time consuming.